The present invention relates to a rolling guide apparatus, such as a linear guide apparatus or circular guide apparatus.
A rolling guide apparatus comprises a first slide member including a pair of wing portions opposed to each other and a second slide member capable of moving relatively to the first slide member. A plurality of rolling elements, such as balls, are held between the wing portions of the first slide member and the second slide member.
For example, a linear guide apparatus includes a carriage as an example of the first slide member and a rail as an example of the second slide member. The carriage can relatively move in the axial direction (longitudinal direction) of the rail. The carriage includes the pair of wing portions and a connecting portion that connects the wing portions. First raceway grooves are formed individually on the respective inner surfaces of the wing portions. Second raceway grooves corresponding in position to the first raceway grooves are formed individually on the opposite side faces of the rail. Further, the carriage is formed having return ways that are continuous with the first raceway grooves, individually. The return ways and the first and second raceway grooves constitute an endless circulation way. The balls as the rolling elements are held in the circulation way.
In order to enhance the stiffness of the rolling guide apparatus described above, the rolling elements are held under a pre-load between the first and second slide members. Conventionally, the pre-load is adjusted by selecting the size of rolling elements. More specifically, a lot of types of rolling elements with different diameters are prepared, and rolling elements with a suitable diameter are selected and incorporated into the rolling guide apparatus so that a desired pre-load is applied to the rolling elements. In general, the diameters of available rolling elements are graduated in micrometers.
Since the aforesaid conventional pre-load adjusting means involves preparation of a lot of types of rolling elements, its management takes much labor. Moreover, the range of dimensions of the available rolling elements is limited, so that the adjustable pre-load level is inevitably restricted.